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| Paper: |
Origins of Disks in Simulations of Spiral Galaxies |
| Volume: |
480, Structure and Dynamics of Disk Galaxies |
| Page: |
97 |
| Authors: |
Sales, L. V. |
| Abstract: |
We explore the factors that determine the morphology of galaxies
within the ΛCDM scenario using the cosmological
hydrodynamical simulations GIMIC to study the assembly and
evolution of about 100 objects with masses comparable to the Milky Way. At
z = 0, galaxies show a wide variety of morphologies, from
dispersion-dominated systems to archetypical disk galaxies. Contrary to
common belief, the present-day morphologies are only poorly
correlated with the properties of the dark matter halos (such as
merger history, assembly, and overall spin). Instead, we identify two
important factors that determine the present-day morphologies: i)
the alignment of the angular momentum of the baryons that accrete
over time to form the galaxy, and ii) the fraction of baryons
accreted via the hot corona. Disks tend to form when the spin of
newly-accreted gas is well aligned with that of the galaxy already
in place, whereas misalignments drive the growth of spheroids. The
mode of gas accretion is also important. Disks form in halos where
the contribution of hot accretion is maximized. This follows as
cooling of gas from the hot-phase provides a slower channel of
gas supply that guarantees its availability at later times to build up the
young star-forming disks that we observe today. |
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